A model of the energy system of lactating and pregnant cows

Bruce, J. M.; Broadbent, P. J.; Topps, J. H.

doi:10.1017/s0003356100041544

Cited by 39 publications

(15 citation statements)

References 10 publications

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“…Body weight was recorded weekly using an electronic weighting scale. Body weight was adjusted for the weight of the foetus at day g of gestation using the formula of Bruce et al (1984) assuming a calf weight of 40 kg Log 10 Foetus weight ð Þ ¼ 2:932 À 3:347e À0:004064g…”

Section: Data Recording and Editingmentioning

confidence: 99%

Phenotypic profiles for body weight, body condition score, energy intake, and energy balance across different parities and concentrate feeding levels

2006

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Section: Data Recording and Editingmentioning

confidence: 99%

Phenotypic profiles for body weight, body condition score, energy intake, and energy balance across different parities and concentrate feeding levels

2006

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“…Dry matter intake and diet metabolizable energy content, estimated from daily feed intake, were used to calculate gut fill. Weight of conceptus was estimated based on days of pregnancy, using the formula of Bruce et al (1984). Body protein and lipid change were estimated by subtracting the current estimate weekly from the previous week.…”

Section: Datamentioning

confidence: 99%

Genetic Profile of Total Body Energy Content of Holstein Cows in the First Three Lactations

Banos

Brotherstone

Coffey³

2005

Journal of Dairy Science

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Weekly total body energy content (TBEC) was calculated for 444 Holstein cows in their first 3 lactations. These calculations were based on body lipid and protein changes predicted from weekly changes in body condition score and live weight of each cow. In first lactation, cows lost TBEC during the initial 8 wk, regained it by wk 22, and continued to build up their reserves until wk 37. Cows started lactations 2 and 3 with considerable reserves from the dry period that they used during the first 13 wk of lactation. Variance components for TBEC were estimated using random regression analysis allowing for heterogeneous residual variance. The genetic variance increased within each lactation, suggesting that the genetic component becomes more important as lactation progresses. The genetic correlations between very early (wk 1 to 4) and later stages of first lactation were near zero but they increased considerably between later lactation stages. Genetic correlations between TBEC on wk 5 of first lactation and the remainder of this lactation ranged from 0.64 for the more distant weeks to 0.99 for the immediately subsequent weeks. Genetic correlations with TBEC in second lactation were moderately high (0.68 to 0.70) for the early weeks (1 to 8) and decreased gradually to 0.56 for weeks at the end of lactation. For third lactation, these estimates ranged from 0.53 to 0.63. Genetic correlation estimates of TBEC in wk 12 of first lactation with subsequent first-lactation weeks varied from 0.79 to 0.99, whereas they ranged from 0.65 to 0.77 and from 0.57 to 0.68 in second and third lactations, respectively. The genetic correlation between TBEC in later weeks of first lactation and the rest of productive life increased as first lactation progressed, but the improvement di- 2616TBEC were used to predict second-and third-lactation energy content. The accuracy of these predictions increased with progressing weeks in first lactation, but about three-fourths of the improvement occurred by wk 5. Our results suggest that TBEC calculated after a month from the first calving may give useful information about the future energy content of a cow. (Key words: total body energy content, genetic variation, lactation, dairy cattle) Abbreviation key: LWT = live weight, TBEC = total body energy content.

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“…The model of Bruce et al [8] is an example in which main fluxes of energy are taken into account (maintenance, pregnancy, lactation and body reserves), intake being considered as a fixed input. The energy balance is expressed as I = C+B+M+Q where I, C, B, M, and Q are respectively energy input, energy retained as conceptus, energy retained in body reserves, energy exported in milk and heat production.…”

Section: Energy Utilisation and Storage; Body Condition Scorementioning

confidence: 99%

Modelling the performance of the beef cow to build a herd functioning simulator

Agabriel

Ingrand²

2004

Anim. Res.

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-This review deals with the representation of the individual animal in herd scale models for cattle. One main problem in these models is to connect two levels of complexity: herd functioning at the farm level and functioning of the individual animal when physiological processes are considered. The text deals first with the representation of the animal and its physiological functions within existing models. Different physiological functions (i.e., growth, intake, lactation and breeding) are rarely modelled in a mechanistic way when used at the herd level, but mostly on an empirical basis, according to classic mathematical laws. The breeding function is the most important one (since it allows for herd renewal) and is frequently modelled as a stochastic process. The body condition score is a relevant indicator of the cow's status, which requires a better representation in individual-based models. Some herd models are presented and discussed and some proposals are presented for a herd functioning model for beef cattle taking into account both animal performance and decisional processes.cattle / herds / cow model / herd models Résumé -Modéliser la performance de la vache dans un simulateur de fonctionnement de troupeau allaitant. Cette revue rassemble les différentes manières d'envisager la représentation de l'animal au sein des modèles de simulation de troupeau. Un des problèmes majeurs est en effet de bien faire correspondre deux niveaux de complexité potentielle : celle du fonctionnement du troupeau au sein de l'exploitation agricole, et celle du fonctionnement de l'animal selon la finesse de description des mécanismes biologiques. Ce texte envisage d'abord la manière dont l'animal et ses différentes fonctions physiologiques sont prises en compte dans les modèles existants. Les fonctions de l'animal (croissance, ingestion, lactation) sont rarement modélisées de façon mécaniste, mais plutôt sur la base d'ajustements empiriques selon des lois mathématiques classiques. La reproduction a une place prépondérante car elle gère la dynamique du troupeau simulé. Elle se modélise le plus souvent de façon stochastique. La note d'état est un indicateur fiable des performances individuelles de la vache qu'il faudrait bien savoir représenter pour développer de meilleurs modèles individuels. Ensuite, les modèles développés à l'échelle du troupeau sont présentés et discutés, pour au final, formuler des propositions pour le développement d'un simulateur individu centré intégrant la modélisation du fonctionnement de l'animal en relation avec les décisions de l'éleveur.bovins allaitants / troupeaux / modèle vache / modèle troupeau * Corresponding author: aga@clermont.inra.fr 348 J. Agabriel, S. Ingrand

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A model of the energy system of lactating and pregnant cows

Cited by 39 publications

References 10 publications

Phenotypic profiles for body weight, body condition score, energy intake, and energy balance across different parities and concentrate feeding levels

Phenotypic profiles for body weight, body condition score, energy intake, and energy balance across different parities and concentrate feeding levels

Genetic Profile of Total Body Energy Content of Holstein Cows in the First Three Lactations

Modelling the performance of the beef cow to build a herd functioning simulator

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